package servlet;

import pojo.User;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

@WebServlet(urlPatterns = {"/user"})
public class UserServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        //集合
        List<User> users = new ArrayList<>();

        //JDBC操作
        try {
            //1.加载驱动
            Class.forName("com.mysql.cj.jdbc.Driver");

            //2.获取连接
            String url="jdbc:mysql://127.0.0.1:3306/jdbc?characterEncoding=utf-8";
            try {
                Connection con = DriverManager.getConnection(url, "root", "123456");
                if(con!=null){
                    System.out.println("连接成功");
                }

                //3.写sql
                String sql="select * from user2";

                //4.预编译sql
                PreparedStatement preparedStatement = con.prepareStatement(sql);

                //5.有参数设参数

                //6.执行sql
                ResultSet resultSet = preparedStatement.executeQuery();

                //7.建立结果集
                while(resultSet.next()){
                    User user = new User();
                    user.setId(resultSet.getInt(1));
                    user.setName(resultSet.getString(2));
                    user.setPassword(resultSet.getString(3));
                    //将对象添加到集合当中
                    users.add(user);
                }

                //8.关闭资源
                resultSet.close();
                preparedStatement.close();
                con.close();

                //把集合中的数据存储到作用域中
                req.setAttribute("users",users);
                //打开页面
                req.getRequestDispatcher("/user.jsp").forward(req,resp);

            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        }
    }
}
